As the recent network technology advances, information transmission networks have been put to practical use in various fields. The fields contain a railway traffic field that requires high reliability and high safety. In such a field, a transmission failure may cause a serious influence. Therefore, such a field has required a high-reliability information transmission system that will never stop even when multiple failures occur.
Routing and spanning tree algorithms in Ethernet as general-purpose network technologies have been well known as transmission technologies that enable uninterrupted transmission when multiple failures take place. Further, a network technology for railway vehicles has been disclosed in Japanese Application Patent Laid-Open Publication No. Hei 11-154891.
This patent is characterized by providing two transmitters in each railway vehicle, loop-connecting said transmitters as a first transmission line in each vehicle, and connecting two terminals as a second transmission line in each vehicle, whereby, when said first transmission line becomes faulty, said second transmission line is used as an alternative line to continue transmission.